Intravascular catheters are used to penetrate the vascular system of a patient for a wide variety of therapeutic purposes. Particularly with those catheters which penetrate the arterial side of the cardiovascular system, steps must be taken to prevent back leakage of blood out of and along the catheter because of the higher arterial pressures.
To accomplish this, it has been conventional to provide a catheter sheath introducer such as is disclosed in Stevens U.S. Pat. Nos. 4,000,739 and 4,421,296, Hillstead U.S. Pat. No. 4,895,565, and the like. This type of arterial catheter, the catheter sheath introducer, has a relatively short catheter shaft, a proximal housing, and an elastomeric partition valve secured in the housing and carrying a slit. Thus, another catheter can extend through the slit in the partition valve, and through the entire catheter sheath introducer, to be inserted into the arterial system of the patient while the elastomeric partition valve prevents the back bleeding of blood through the annular space that exists between the two catheters.
Catheters may be inserted and withdrawn through the catheter sheath introducer, which reduces trauma to the patient relating to the repeated motion of catheters in the arterial system. Additionally, guidewires may be inserted through the catheter sheath introducer into the arterial system of the patient.
Disadvantages have been noted in previous designs of catheter sheath introducers, in that some slit configurations do not stop the leakage well. Also, it is desirable for the friction to be minimized as a catheter advances through the elastomeric partition valve. If the friction is high, the manipulation of catheters through it is impeded, and the partition valve may rip, causing it to fail.
By this invention, a new design of elastomeric partition valve for a catheter sheath introducer, or any other desired intravascular catheter, is provided. The new elastomeric partition valve exhibits a very low advancing friction when a catheter or a guidewire is being advanced through and into the patient. However, the same partition valve exhibits an improved capability to resist back leakage of blood at arterial pressures, when compared with other types of partition valves for this purpose.